Standard rotary drilling rigs typically comprise a supportive rig floor, a derrick extending vertically above the rig floor, and a traveling block that can be raised and lowered within the derrick. During drilling operations, such rig equipment is often used to insert, and/or remove, pipe from a well that is situated under the derrick. For example, drill bits and/or other equipment are often lowered into a well and manipulated within such a well via a drill string. Furthermore, once a well has been drilled to a desired depth, large diameter tubulars or pipe (e.g., casing) can be installed in the wellbore and cemented in place in order to provide structural integrity to the well, isolate downhole formations from one another and prevent contamination of the well.
When installing a pipe string (e.g., casing, drill pipe, or other tubulars) into a well, the length of a pipe or tubular is typically installed individually, for example, in a section of pipe. Each pipe section can be threadably joined to another pipe section, by the use of couplings or other connectors, to form a continuous pipe string. In order to start the process of inserting joints of pipe into a well for forming a pipe string, a first joint of pipe is lowered into the wellbore and suspended in place using a set of lower slips. The slips can comprise wedge-shaped members for grasping and positioning the pipe. The lower slips can be positioned adjacent to the rig floor, for example, within a spider or a bowl-shaped housing of a rotary table. The lower slips can be operated through automation or can be inserted and removed manually by an operator. It should be understood that the individual joint of pipe can include a drill pipe, a casing section, or other tubular member usable in downhole operations. As the individual joints of pipe are connected to form a string of pipe, the lower slips can be used to hold the weight of the entire pipe string and can be used to suspend the entire pipe string in the wellbore.
During the process of installing joints of pipe into a wellbore, an individual joint of pipe can be inserted into the wellbore and positioned so that the top of the joint of pipe is located above the rig floor. A pipe handling machine can be used to grab another joint of pipe, lift that joint of pipe vertically, and position and align that joint of pipe above the joint of pipe that was previously run into the wellbore, for forming the pipe string.
The two joints of pipe can be joined together by threadably engaging the lower end of the upper joint of pipe with a coupling or connector, which is threadably attached to the upper end of the lower joint of pipe (i.e., stabbing process). Thereafter, the upper joint of pipe can be rotated, for mating the threaded connection between the upper joint of pipe and the coupling or connector that is attached to the lower joint of pipe, to form the pipe string.
Thereafter, an elevator, comprising a central cavity and a set of upper slips, can be positioned and lowered over the upper joint of pipe. The central cavity can be aligned with the top section of the upper joint of pipe, and the upper slips can be used to grip the outer surface of the upper joint of pipe. Depending on the length of the joint of pipe, the elevator can grip the joint of pipe at a position of approximately forty feet or more above the rig floor.
Once the elevator slips are engaged around the outer surface of the joint of pipe, the elevator can be raised, using, for example, a traveling block on a rig, for lifting the pipe string and eliminating the weight that was on the lower slips. Then, the elevator can be used to lower the pipe string to a desired distance within the wellbore, and the lower slips can be positioned, again, for gripping the lowered pipe string. The process can be repeated until the desired length of pipe is inserted into the wellbore.
At certain points during this process, the entire weight of the pipe string is being held or suspended by the elevator and, more specifically, by the elevator slips. The pipe string can be extremely heavy, especially when a large number of joints of pipe (tubular members), having a large diameter and/or thick-walls, are being run into the wellbore. Accordingly, it is important that the elevator slips are properly positioned along the length of each joint of pipe, and are set properly around the outer surface of each joint of pipe, to ensure that the joint of pipe is secured within, and gripped by, the elevator to avoid damage to the rig and/or injury to the operators. For example, if the joint of pipe is not properly secured within the elevator, the joint of pipe, or the entire pipe string, could be dropped by the elevator, thereby causing severe damage to the rig or wellbore and/or causing injury to the rig personnel.
In many cases, an end of a joint of pipe can comprise a drill collar, which can include a female or box-end threaded connector or coupling for joining to another joint of pipe. The coupling or connector can have a larger outer diameter than the remainder of the joint of pipe. In order to properly engage the upper or second joint of pipe with the lower or first joint of pipe, the elevator slips should be engaged against the outer surface of the upper joint of pipe, below the thickened portion where the coupling or connector is positioned. If the elevator slips, or any portion(s) thereof, are closed against the coupling or connector, or any other protrusion or thicker portion (i.e., drill collar) of the joint of pipe, the elevator slips may not fully contact and/or properly engage the outer surface of the joint of pipe. As a result, the elevator slips may not properly engage against the joint of pipe, and may not grip the pipe securely, such that the weight of the joint of pipe, or the entire pipe string, is not supported and is subsequently dropped. Accordingly, it is imperative that the elevator slips are properly positioned for securing each joint of pipe and/or pipe string to avoid any of the risks associated with dropped pipe and/or pipe strings, including damage to the rig and/or wellbore and/or injury to the rig personnel.
One method of installing pipe into a wellbore involves a “derrick man” or operator, who is stationed on a platform within the derrick, at approximately the height where the elevator slips are closed about the outer surface of a joint of pipe, which can often be approximately forty feet or more above the rig floor. The derrick man visually observes when the elevator has been properly positioned over the top of the joint of pipe and lowered, relative to the outer surface of the joint of pipe, for gripping a section of the joint of pipe. The “driller,” who is located on the drill floor, controls the vertical positioning of the traveling block, and the elevator attached thereto. Once the derrick man observes that the elevator has been properly positioned, relative to the section of the joint of pipe for proper gripping, the derrick man then communicates this information to the driller. With the elevator is positioned and lowered over the top of the joint of pipe, the elevator slips are closed around a section of the joint of pipe for gripping the individual pipe. Thereafter, the driller can pick up the elevator, thereby lifting the entire pipe string. In other cases, the positioning of the elevator, relative to the joint of pipe, can be determined by using video cameras mounted in the derrick, wherein the video cameras can provide a video image of the elevators to the driller or other rig personnel.
As described above, it can be difficult for the driller or other rig personnel to determine whether an elevator is properly positioned relative to the top of a joint of pipe suspended within the derrick, which can lead to risks associated with damage to the rig or wellbore and/or injury to rig personnel. Further, it is often difficult for a derrick man to judge when an elevator is properly positioned relative to a joint of pipe, suspended within the derrick, even though the derrick man may be positioned on an elevated platform in the derrick, which can also lead to risks associated with damage to the rig or wellbore and/or injury to rig personnel. Furthermore, there can be additional risks associated with human error and/or miscommunication between the derrick man and the driller, especially when shouts or hand signals are required for communicating.
Accordingly, there is a need for apparatus and methods usable for accurately determining when elevators and/or spiders, and more particularly the slips of elevators and/or spiders, are positioned in a desired location, along a joint of pipe. These apparatus and methods are needed for properly gripping and lifting and/or holding the joint of pipe to avoid damage to the rig and/or wellbore and/or injury to rig personnel.
In addition, there is a need for apparatus and methods usable for automatically setting and closing the slips about a desired section of a joint of pipe for proper positioning and full engagement of the slips along the desired section of the joint of pipe.
Further, there is a need for an apparatus that is usable to forceably secure a plurality of slips of a spider against a tubular, for proper positioning and full engagement of the slips along the desired section of the joint of pipe.
Furthermore, there is a need for apparatus and methods, which can be usable for signaling a driller and/or other rig personnel when such elevator slips are securely positioned along, and relative to, the desired section of the joint of pipe for properly engaging, gripping and lifting the joint of pipe. Such apparatus and methods can include indicating when the elevator slips have passed over an external coupling or other thicker/irregular portion of a joint of pipe (e.g., drill collar), such that the elevator slips are now located at the desired section of the joint of pipe joint for proper engagement, gripping and lifting of the joint of pipe.